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MG Midget and Sprite Technical - The dreaded oil leaks

Just a bit of an update on this perennial problem. The most persistent leak on my small bore block is from the front side cover. I use the 1098 cover with the oil separator, but with a thin gasket it fouls the front plate and won't seal. I tried the thick rubber gasket, but that doesn't fit the cover very well and usually slips out or in. The thick cork gasket often does the same, but I had one more try as that was the only gasket I had. This time I fitted it to the cover with good quality silicone, and bolted it to the spare engine (a gentleman always has a spare engine). It's incredibly difficult to fit to the engine in the car, as the exhaust manifold gets in the way. Yes I could remove the manifold, but it has been sealed to the pipe and as it's an LCB I have to remove the heater box to get enough room to remove it.

Anyway, after the silicone was cured the cover could come off the spare engine, and the cork was firmly fixed to it. It's a tight fit to the cover and has to be stretched slightly. It's probably the wrong one for that cover but as I say it's all I had. So it was much easier to fit the assembly to the engine in the car as I didn't have to cope with the gasket sliding all over the place while covered in sealant.

Does it work? I did nearly 200 miles yesterday and no sign of a leak. I am optimistic. You can see why the factory got rid of the side covers on big bore engines, but I still don't understand how you fit the cam followers.

Another very annoying dribble is from the rocker cover hold-down nut seals. Those rubber things always go soggy and leak. They never last more than a year. Where can I get better quality ones?

As reported elsewhere I have given up on the rear main bearing aftermarket oilseal and had the cap and half-moon machined to restore factory tolerances. Good for another 50 years I hope.

PS. I am using only one breather hose, from the oil separator on the side cover, and which goes to the vacuum port on the HIF44. No PCV valve. Is one breather enough? The vacuum port is smaller diameter than the oil separator outlet, and I can't see how an extra breather would add anything, as it would have to use a Y connector. I could fit it to the redundant fuel pump point on the block, but what do you chaps think? That was the setup I had on the old engine, in an attempt to get the useless crankshaft seal kit to work.
Les Rose

" but I still don't understand how you fit the cam followers."

Engine upside down is how.

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"Another very annoying dribble is from the rocker cover hold-down nut seals. Those rubber things always go soggy and leak. They never last more than a year. Where can I get better quality ones? "

Old ones. Mine are yonks old.

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Engine Breather.

"PS. I am using only one breather hose, from the oil separator on the side cover, and which goes to the vacuum port on the HIF44. No PCV valve. Is one breather enough? "

Run the engine. Remove the oil filler cap. Put your hand on the open oil filler hole. Is there suction? If so, it's as good as you are likely to get. It was never perfect. As rev's rise, blowby increases, pressure increases, and defeats the crankcase ventilation. Guy's glove illustrates it really well. But I can't find a pictiure.

Guy?

anamnesis

Thanks Anam, yes I have seen Guy's glove video. I do get suction so will leave the breather as it is.
Les Rose

You can get poly replacements for the rocker box hold-down nut seals.
The HIF44 vacuum port is low vacuum so is OK without a PCV.
I used to have vacuum from front cover and rocker box through a Y pipe into a HIF44 (it was on a 1275 though) but I read (somewhere) that above and below the head the internal pressure pulses are out of sync and detract from generating sufficient -ve pressure in the bottom of the engine. I deleted the rocker outlet (and blocked it off) but didn't notice any change in the dripping so maybe a fairy tale?
Rob
MG Moneypit

Have to say on my 1098 I fitted cork gaskets on the rocker and on the side covers and no leaks yet. Only been 400 miles since rebuild though.

Side cover gaskets were tight to fit as you said. Certainly a lot harder with the inlet manifold in the way.

I’ve noticed a tiny amount of oil on the rubber washers for the rocker bolts, but not enough to drip or run. Those bolts have a very low torque rating so can be over tightened easily, which might make them distort.

I have side oil canister and pcv and twin SU carbs so different set up. Can’t offer any advice on that, sorry.
James Paul

This thread was discussed between 21/08/2023 and 24/08/2023

MG Midget and Sprite Technical index

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